The present invention relates to a polyurethane elastomer actuator for transforming the shrinkage displacement occurring at the time of the application of an electric field into the curvature displacement or the elongation displacement.
Hitherto, a polymer gel actuator using a chargeable gel and an electrochemomechanical actuator using a conductive polymer are known for the advantage of the large deformation in a relatively low electric field. Both, however, require the use in electrolyte, and are accompanied by chemical reactions, including the ionic polarization and the oxidation and reduction, resulting in the poor durability due to heat generated by a current and electrolysis.
Piezoelectric materials including ceramics or polymer materials have been researched and developed for the application to speaker or headphone materials, and actuator elements of sensors, ultrasonic motors or the like. Such materials exhibit excellent performances in specific applications. However, when such materials are applied to an actuator, a high voltage of 10 kV is usually required for driving. Additionally, the amount of the deformation of the actuator is about several micrometers, which gives rise to necessity of a mechanism for magnifying the displacement. Even by forming the actuator into a multilayer structure, such as bimorph type, the obtained displacement amount is not so large, actually about hundreds of micrometers.